One cylinder not firing...tips

No color?
Not firing ... No fuel???
Oily fouling of the Spark Plug?

Check that there's no obstruction in the metering at the bottom of the offending cylinders Fuel Bowl ... that would prevent the WELL from filling with fuel.

Likewise ... probe the slender, brass Siphon Tube for obstruction. This is looking like no fuel getting up-top.

Push some spray carb cleaner through All those ports.

 

If during the colortune you closed the mixture screw all the way in and didn't get a miss fire then it has to be getting fuel from somewhere. Without a vacuum petcock then the only other sources I know of is the float height or a leaking choke plunger or as fooglebinder said the screw is damaged.
When checking float height you need to let the fuel stand for a minute and see if it rises. This is the way to check for a leaking float valve. A high fuel height will allow fuel to drown the pilot jet and therefore bypass the mixture screw.
If the oring is damaged this would allow air to be sucked in from the top of the mixture screw and may not allow an orange flame. The higher you raise the screw the more air can get in. It will therefore be sucking air from a point past the fuel source, weakening the draft on the fuel so that no more fuel gets into the stream.

 

I don't know about anybody else ... but, I'm a bit confused; here?

The ColorTune -- IS -- Blue?
But, the 3 Cylinder misses, fouls a plug and the 3 exhaust is cooler than the others???

Swap the connections to the Coils and see if it will run better on the opposite set of coils. If it does ... dial-in 3 with the ColorTune while she's running good this way.

If you find that the problem shifts-over to #2 (or 4) ... You need to shake-down the ignition problem you're having.

 

I am too Rick. But I have been through this before and usually something creeps in that finally makes things make sense. One of those cases where I wish I could get my hands on the bike and so does the owner!

 

That's my sentiment too. If I could get my hands on that bike, then it might be alot easier.

Sorry, but when we help from afar all we can do is suggest blindly and go strictly by what you observe and communicate.


btw, my bike started to do something like what youre saying only on the #4 cylinder. cold pipe and all. I found the sparkplug cap had started to come apart from the wire, simple tighten and replaced plug and smooooth again.

 

Believe me, I wish you guys could get your hands on it too. I'm kinda running blind on this as well. ;-) H*ll, everytime I do something to it I run in to my computer to get an update from the gurus. ;-)

I'll try switching the wires tomorrow and see if it helps any. When you say swap the wires, you mean take 1/3 and put it on 2/4 and vice versa, correct?

Sparkplug cap: I'm assuming that by this you mean the cap at the end of the wire coming from the coil that hooks onto the plug itself, correct? I'm really not this much of a bonehead when it comes to mechanical stuff, I just don't know the terminology for some of it. ;-) And I know next to nothing about bikes. Good combo, huh?

 

You can swap the plug wires and caps between #2 and #3 (the middle two). If your problem moves to #2 then you know to look at the cap, wire, coil.

 

any update on the problem? Is it fixed? I am having the same issue, but I can see my coil is cracked.

 

So far, no updates. I've switched the wires as was suggested and it didn't help the situation. The last time I went out to check things out, I rechecked the floats and everything was just about perfect. The real pisser, I started up the bike and all 4 cylinders seemed to be working great. Took it around the block a couple of times and it ran ok, but it seemed to be surging a little. I'm hoping that I can get a local bike guy to take a look at it and give me his opinion on what I'm doing wrong.

 

If the situation is IMPROVING ... you're doing "something" ... RIGHT!

 

That's what I'm hoping. The only thing is, I can't figure out what I did to make all 4 cylinders fire. I've asked this a few times before, but never really gotten an answer, is it possible for a bike to only fire on 2 or 3 cylinders when you first start it up, but then once it warms up, all 4 kick in? If so, what would be the typical remedy for the initial non firing situation?

 

A clogged siphon tube or the metering ports in the bottom of the fuel bowl that allow fuel to rise in the fuel bowl well where the siphon tube extends down in to.

Loose set screw on enrichment valve activating fork allowing rod to rotate without lifting-up the enrichment valve body.

Bad spark plug, wire, cap, coil.
Bad coil ground.
Moisture inside cover causing difficulty with pick-up signal.
Pinched pick-up's wiring along the path to the ignitor.

Bad connection between harness and coils. Quick-connects corroded.

 

The good thing is, that you live in or near a large metro area.

There are no shops per say where I am, nearest big city is oveer 100 mi away.

 

If you switched the 2 & 3 plug wires then the problem is either fuel or spark plug.

I found (at least before my overwinter tune up) that periods of low RPM operation could foul a plug preventing firing. High RPMs and temps would clean it up. Oh, mine don't have to look very fouled to not fire either.

Surging is fuel/air. Thread is getting old so I don't remember:

Did you check valve clearances?

Sync?

 

where is that post or how-to on changing the wires in the stock coil housing? I remember it showing how you had to cut the casing then re-seal it up afterwards. I have a new coil on the way, but I wanted to hack apart the old one and see what's up inside there....possibly fix it for a spare.

thanks

 

Nothing to loose PghXJ, go for it. If nothing else, you could possibly repair the coil and press it back into service as an emergency back-up (this is provided it is the secondary lines that are shot, if the primary is burned out, it's done).

 

I have not checked the valve clearances. Admittedly, I'm a little nervous to break into that, but it might be my next step.

As far as the sync, I bench synced it when I took the carbs down and cleaned them, but I haven't been able to guage them yet as I am lacking the guages.

 

I believe the pimary is good, and one of the secondaries is shot.

so, does anyone know where that how-to is on cutting up the coil and reattaching new secondary wires?

 

Valves arn't too bad to check.

To sync buy 12 feet or so of clear tube the size that will fit over the vacuum attachments on the intake boots, attach the tube to a broomstick so it is a U shape, fill with 2 stroke oil to have 3 feet of oil in each side. Get bike warm, increase idle to 1300-1400 RPM and sync 2 carbs at a time (3 & 4, 1 & 2, 2 & 3) cost me NZ $4 for the tube.

 

Here you are:

Coil lead replacement

Hope that helps!

BTW the solid core lead is $1 a foot here